CSPP1 and colorectal carcinoma: When we cloned the circ-CSPP1 segment containing the target region into a luciferase vector, the cotransfection of the luciferase reporter (WT-circ-CSPP1) and miR-431 mimic into the two CRC cells produced lower luciferase activity than cells cotransfected with mimic control, but the mutant in the seed region (MUT-circ-CSPP1) completely abolished the downregulated impact of miR-431 mimic (Figure 3b and c).